The three things that drew people to New York en masse - opportunities, food and culture - have all now been wiped out.
Businesses have realized they can continue to operate successfully with a remote staff. There are few that have returned as a result.
With no requirement to stay in the city for their jobs, many are unwilling to put up with the escalating crime.
One man wrote in a Facebook group: 'In the last week: I watched a homeless person lose his mind and start attacking random pedestrians. Including spitting on, throwing stuff at, and swatting.
'I’ve seen several single parents with a child asking for money for food. And then, when someone gave them food, tossed the food right back at them. I watched a man yell racist slurs at every single race of people while charging, then stopping before going too far.'
Another said: 'I’ve been living in New York City for about 10 years. It has definitely gotten worse and there’s no end in sight.
'My favorite park is Madison Square Park. About a month ago a 19-year-old girl was shot and killed across the street.
'I don’t think I have an answer but I do think it’s clear: it’s time to move out of NYC.
'I’m not the only one who feels this way, either. In my building alone, the rent has plummeted almost 30% — more people are moving away than ever before. So…
'It’s not goodbye yet. But a lifelong New Yorker is thinking about it.'
Altucher said he was not tempted to leave until June, when riots and looting took over the city for a week.
'Nothing was wrong with the protests but I was a little nervous when I saw videos of rioters after curfew trying to break into my building,' he wrote.
He has now moved with his family to south Florida and is unsure if they'll come back.
'I’m temporarily, although maybe permanently, in South Florida now. I also got my place sight unseen,' he wrote.
His comments come as the NYPD's largest union - the Sergeants Benevolent Association - has taken the unorthodox step of formally endorsing Trump because cops are so frustrated with de Blasio's handling of the city.
In June, he stripped the NYPD of $1billion in response to Black Lives Matter protesters who wanted to defund the department entirely.
Trump has vowed to revitalize the city if he wins the November election, but he hasn't yet explained how. De Blasio remains in power until November 2021. He cannot be re-elected.
On Monday morning, the President phoned into Fox & Friends to discuss a range of issues, including New York City.
'The mayor has no response. He doesn't know what he's doing, he's a fool.
'He's a socialist, communist maybe he's a fool. He got rid of some of the most talented policemen that there are in the world and that includes looking for very bad things all beyond New York.
'Some of those people are gone and that's no good. No, this is a fool. This is a fool.' he said of de Blasio.
Crime has shot up in recent weeks, particularly shootings. There were more than 60 shootings across New York City in the last week, leaving 76 people injured.
Trump said on Monday: 'Look at the shootings. When I left New York four years ago, New York was, I could see the seeds of this because he's been a bad mayor but new York was good.
'It was okay. It all happened recently. It all came together. All of this over a period of years as he's been mayor, but about a year, and then six months ago, it's incredible what happened.
'When I left New York four years ago, we were doing great. I was doing good. Everybody was doing good. Now but you could see the seeds were being sewn.